The present invention relates to a thin film magnetic recording head used for recording and reproducing in a magnetic disk drive or the like and a magnetic disk drive mounted therewith.
In a magnetic disk drive, data on a recording medium is read and written by a thin film magnetic head. In order to increase a recording capacity per unit area of a magnetic disk, it is necessary to form an area recording density in a high density. However, according to a current longitudinal recording system, when a length of a bit to be recorded is reduced, there poses a problem that the plane recording density cannot be increased owing to thermal fluctuation of magnetization of a medium.
In order to solve the problem, there is provided a perpendicular recording system for recording a magnetization signal in a direction perpendicular to a medium. Also in the perpendicular recording system, in reproduction, there can be used a magnetoresistance effect type head (MR head) and a giant magnetoresistance effect type head (GMR head) having a large reproduced output. Meanwhile, in recording, it is necessary to use a single pole type magnetic head. Also in perpendicular recording, it is necessary to increase a tracking density and a line recording density in order to increase the recording density. In either of them, in order to increase the tracking density, it is necessary to form a track width of the magnetic head very finely and highly accurately.
Further, in perpendicular recording, there poses a problem that noise is generated by an external magnetic field or the like. For example, there is a description with regard to a spike noise from an external magnetic field in xe2x80x98Japanese Patent Application Laid-Open No. H07-225901xe2x80x99. After the noise is detected, the noise is canceled. Further, the problem of noise after recording is also considered to be derived from that a magnetic domain of a main pole is unstable and the magnetic domain is moved. There is a description with regard to a single pole type head having a shield for resistance against external magnetic field in xe2x80x98Digest of 24th Conference of Japan Society of Applied Magnetics (P161)xe2x80x99.
According to a proposal of xe2x80x98Japanese Patent Application Laid-Open No. H07-225901, there is disclosed means for detecting a spike noise and avoiding error and there is no description with regard to a reduction in the noise at the magnetic head. Further, there poses a problem that a main pole is magnetized by an external magnetic field, a magnetic field thereof is leaked to a medium and the magnetization signal on the medium is erased.
As a countermeasure thereagainst, in xe2x80x98Digest of 24th Conference of Japan Society of Applied Magnetics (P161)xe2x80x99, there is disclosed a structure of providing a shield against the external magnetic field in the single pole head. According to the structure, the shield against the external magnetic field is constructed by a structure of being exposed to a surface against the media. Therefore, although there is achieved a significant effect for preventing the external magnetic field from entering the main pole, there also poses a problem that the shield against the external magnetic field collects the external magnetic field, the external magnetic field leaks from the surface against the media to the media, the magnetization signal of the media is erased or a signal is written. Further, there also poses a problem that a magnetic field in recording is leaked from the main pole and leaked to the media via the shield against the external magnetic field.
Hence, it is an object of the invention to provide a thin film magnetic recording head having a perpendicular recording head in which noise by external field is eliminated and a shield for preventing the noise does not leak magnetic field to a medium and a method of fabricating the same as well as a magnetic disk drive having high stability mounted with the perpendicular recording head.
In order to achieve the above-described object, according to an aspect of the invention, there is provided a thin film magnetic recording head comprising a single pole type perpendicular recording head including an auxiliary pole, a main pole and a shield against an external magnetic field, wherein an edge of the shield against the external magnetic field is provided at a position recessed at least from an edge of the main pole relative to a surface against a medium.
Further, according another aspect of the invention, there is provided a thin film magnetic recording head including a reproducing head using a magnetoresistance effect and a single pole type perpendicular recording head, wherein the perpendicular recording head includes an auxiliary pole, a main pole, a shield against an external magnetic field, a first gap layer formed between the auxiliary pole and the main pole and a second gap layer formed between the main pole and the shield against the external magnetic field, and wherein a width of the auxiliary pole opposed to the first gap layer is larger than a width of the main pole opposed to the first gap layer and an edge of the shield against the external magnetic field is provided at a position recessed at least from an edge of the main pole relative to a surface against a medium.
Further, according to another aspect of the invention, in the above-described constitution, an amount of recession from the surface against the medium of an edge of the shield against the external magnetic field falls in a range of 0.5 through 3 xcexcm at a portion thereof opposed to the main pole, further, an interval of a gap formed between the main pole and the shield against the external magnetic field falls in a range of 0.5 through 3 xcexcm, further, a position of the edge of the shield against the external magnetic field in a direction remote from the surface against the medium, is disposed to be remote from a position of the edge of the main pole in the direction remote from the surface against the medium by 1 through 10 xcexcm.
Further, according to another aspect of the invention, there is provided a method of fabricating a thin film magnetic recording head including a perpendicular recording head having an auxiliary pole, a main pole and a shield against an external magnetic field, the method including a step in which the shield against the external magnetic field is formed by using an electroplating method with photoresist frame and formed such that an edge of the shield against the external magnetic field is disposed at a position recessed at least from an edge of the main pole relative to a surface against a medium.
Furthermore, according to another aspect of the invention, there is provided a magnetic disk drive constituted to execute recording and reproducing by a thin film magnetic recording head, wherein the thin film magnetic recording head includes a single pole type perpendicular recording head which includes an auxiliary pole, a main pole and a shield against an external magnetic field and in which an edge of the shield against the external magnetic field is provided at a position recessed at least from an edge of the main pole relative to a surface against a medium.